One of the main obstacles to the development of quantum technologies is the
decoherence associated to losses and absorption processes occurring during the
propagation of a quantum signal. The description of the dynamics of systems
subject to noisy environments [1]}, as well the detection,
quantification and estimation of losses and, more generally, the
characterization of lossy channels at the quantum level, received much
attention in the recent years [1]}, [3]}, [4]}, [5]}. An
efficient characterization of decoherence is relevant for quantum repeaters
[6]}, quantum memories [7]}, cavity QED systems
[8]}, superconducting quantum circuits [9]}, quantum
teleportation [10]}, quantum cryptography [11]}, [12]} and
secret-key capacities [13]}, [14]}.
